This invention relates to a semiconductor device and for example, it is preferably used for a semiconductor device with a Physical Unclonable Function (PUF) mounted.
The Physical Unclonable Function (PUF) is an artificial object of outputting intrinsic value (response signal) in reply to a given input (challenge signal), by using an uncontrollable small difference of intrinsic physical properties. By using the PUF property, a cipher and authentication function can be realized at a low cost.
In the PUF (hereinafter, referred to as “silicon PUF”) using a semiconductor element, by using variations of the properties in the individual semiconductor elements, intrinsic identification information can be output from the semiconductor circuits of the same design.
As a concrete silicon PUF, Arbiter PUF, Ring Oscillator PUF, and Butterfly PUF are well known. The Arbiter PUF uses variations of signal delays in a signal propagation route using semiconductor circuits. The Ring Oscillator PUF uses variations of oscillation frequencies in ring oscillators. The Butterfly PUF uses variations in the initial state of a latch circuit at the power on (for example, refer to FIGS. 4 to 6 and the related article of Japanese Unexamined Patent Application Publication No. 2011-198317).